Casing removal tool and methods of use for well abandonment

Abstract

Systems and methods for removing casing from a wellbore including a casing removal tool that includes a tubular body configured to contain a thermite fuel mixture configured to initiate into a molten thermite fuel. The casing removal tool also includes a nozzle array having a plurality of nozzles positioned on an external surface of the tubular body. The nozzle array is configured to impinge the molten thermite fuel from within the tubular onto the wellbore casing. The casing removal tool also includes an orientation lug configured to anchor into a downhole orientation tool.

What is claimed is: 
     
       1. A casing removal tool for a rigless removal of a portion of a wellbore casing from a wellbore, comprising:
 a tubular body configured to contain a thermite fuel mixture load comprising a gasifying compound and configured to initiate an exothermic reaction resulting in a molten thermite fuel; 
 a nozzle array comprising a plurality of densely packed nozzles positioned on an external surface of the tubular body, wherein the nozzle array is configured to project the molten thermite fuel onto a section of the wellbore casing so that the molten thermite fuel from each of the nozzles in the plurality of nozzles at least partially overlaps the molten thermite fuel from each adjacent nozzle in the plurality of nozzles; and 
 an orientation lug configured to orient and anchor into a downhole orientation tool comprising a linear and azimuthal orientation keyway, wherein orientation of the orientation lug comprises a change in an azimuthal angle at which the orientation lug interacts with the linear and azimuthal orientation keyway to cause a change in a section of a casing at which said casing removal tool impinges molten thermite fuel onto the section of the casing. 
 
     
     
       2. The casing removal tool of  claim 1 , wherein the orientation lug is configured to be set by an operator at a specific orientation before entering the wellbore. 
     
     
       3. The casing removal tool of  claim 1 , comprising a second nozzle array configured to project the molten thermite fuel onto a second section of the wellbore casing. 
     
     
       4. The casing removal tool of  claim 1 , wherein an area of the nozzle array comprises one quarter of a total area of the external surface. 
     
     
       5. The casing removal tool of  claim 4 , wherein the area of the nozzle array comprises up to a 90° or more rectangular area with the plurality of nozzles uniformly spaced within the rectangular area. 
     
     
       6. The casing removal tool of  claim 1 , comprising a spacer configured to offset the nozzle array a linear offset distance from the downhole orientation tool. 
     
     
       7. The casing removal tool of  claim 1 , comprising a centralizer configured to orient the casing removal tool relative to a radial center of the wellbore. 
     
     
       8. The casing removal tool of  claim 1 , wherein the plurality of densely packed nozzles are in an area on the external surface of the tubular body, and the nozzles occupy more than 50 percent of the area. 
     
     
       9. A method of removing casing from a wellbore with a casing removal tool, comprising:
 lowering and setting a downhole orientation tool in the wellbore, the downhole orientation tool comprising a linear and azimuthal orientation keyway; 
 lowering the casing removal tool into the wellbore, the casing removal tool comprising an orientation lug configured to orient and anchor into the downhole orientation tool; 
 orienting the casing removal tool within the wellbore at a first linear orientation and a first azimuthal orientation by adjusting an azimuthal angle at which the orientation lug interacts with the linear and azimuthal orientation keyway, wherein the casing removal tool comprises a tubular body configured to contain a thermite fuel mixture load comprising a gasifying compound; 
 initiating a burn of the thermite fuel mixture to produce an exothermic reaction resulting in a molten thermite fuel; 
 projecting the molten thermite fuel through a nozzle array comprising a plurality of nozzles positioned adjacent to one another; 
 impinging the molten thermite fuel onto a section of the casing to melt, vaporize, and/or disintegrate the casing, wherein the molten thermite fuel from each of the nozzles in the plurality of nozzles at least partially overlaps the molten thermite fuel from each adjacent nozzle in the plurality of nozzles; and 
 retrieving the casing removal tool from the wellbore. 
 
     
     
       10. The method of  claim 9 , further comprising:
 lowering an additional casing removal tool into the wellbore; 
 orienting, while lowered into the wellbore, the additional casing removal tool within the wellbore, wherein the additional casing removal tool is oriented at a combination of linear orientation and azimuthal orientation that is different from the linear orientation and azimuthal orientation of any previously lowered casing removal tool; 
 initiating a burn of the thermite fuel mixture load within the additional casing removal tool to produce a molten thermite fuel; 
 impinging the molten thermite fuel onto an additional section of the casing, wherein each additional section of the casing is at least partially different from each previous section of the casing; and 
 retrieving the additional casing removal tool from the wellbore before lowering a next additional casing removal tool. 
 
     
     
       11. The method of  claim 10 , wherein each of the casing removal tools is configured to linearly and azimuthally orient based on the downhole orientation tool. 
     
     
       12. The method of  claim 11 , comprising lowering a spacer with each of the casing removal tools to linearly offset each of the casing removal tools from the downhole orientation tool. 
     
     
       13. The method of  claim 12 , wherein the spacer comprises a length to linearly position the casing removal tool relative to a zone of the casing, and wherein the casing removal tool removes at least a portion of the casing in the zone prior to an adjusting of the length of the spacer for the additional casing removal tool or the next additional casing removal tool. 
     
     
       14. The method of  claim 11 , wherein setting the downhole orientation tool comprises perforating holes into the casing with a perforating torch and securing anchor dogs of the downhole orientation tool into the perforated holes, setting a sleeve hanger or a post-positioner with a setting tool, or combinations thereof. 
     
     
       15. The method of  claim 9 , wherein orienting the casing removal tool further comprises offsetting the casing removal tool from a radial center of the wellbore towards the casing. 
     
     
       16. The method of  claim 15 , wherein the casing removal tool is offset toward the section of the casing impinged by the molten thermite fuel. 
     
     
       17. The method of  claim 9 , wherein lowering the casing removal tool into the wellbore comprises using a wireline, a slickline, other rigless tool lowering strings, or combinations thereof. 
     
     
       18. The method of  claim 9 , wherein lowering and orienting the casing removal tool comprises lowering and orienting the casing removal tool by attaching the casing removal tool to an end of a production tubing drill string. 
     
     
       19. The method of  claim 9 , further comprising changing the section of the casing at which said casing removal tool impinges the molten thermite fuel onto the section of the casing by interacting the orientation lug with the linear and azimuthal orientation keyway. 
     
     
       20. A system for removing wellbore casing from a wellbore, comprising:
 a downhole orientation tool configured to be secured within the wellbore, wherein the downhole orientation tool comprises a linear and azimuthal orientation keyway; and 
 a plurality of casing removal tools, wherein each casing removal tool comprises:
 an orientation lug configured to orient within the keyway of the downhole orientation tool, wherein an operator can change a position of the orientation lugs before lowering the casing removal tools into the wellbore, and wherein the change in the position comprises a change in an azimuthal angle at which the orientation lug interacts with the linear and azimuthal orientation keyway to cause a change in a section of a casing at which said each casing removal tool impinges molten thermite fuel onto the section of the casing; 
 a nozzle array comprising a plurality of densely packed nozzles configured to project the molten thermite fuel comprising a gasifying compound onto a continuous section of the wellbore casing after the casing removal tool is lowered into the wellbore; and 
 a spacer configured to offset the nozzle array a linear distance from the downhole orientation tool. 
 
 
     
     
       21. The system of  claim 20 , comprising a second spacer configured to offset the nozzle array a second linear distance from the downhole orientation tool. 
     
     
       22. The system of  claim 20 , wherein the downhole orientation tool comprises a sleeve hanger, a post-positioner, or combinations thereof. 
     
     
       23. The system of  claim 20 , wherein each casing removal tool in the plurality of casing removal tools comprises a nozzle array approximately 6 to 7 meters or more in length and about 90 degrees around an external surface of the casing removal tool. 
     
     
       24. The system of  claim 20 , comprising a centralizer configured to orient the casing removal tool relative to a radial center of the wellbore. 
     
     
       25. The system of  claim 20 , further comprising small splinters of the wellbore casing that are retrieved from the wellbore, removed from the wellbore, or allowed to fall down the wellbore, wherein the small splinters of the wellbore casing are located between the continuous sections of the wellbore casing. 
     
     
       26. A method of removing casing from a wellbore, comprising:
 lowering a casing removal tool into the wellbore through a first wellbore tubing comprising a first diameter, wherein the wellbore comprises the first wellbore tubing and a second wellbore casing, and the casing removal tool comprises a nozzle section; 
 lowering the casing removal tool through the second wellbore casing comprising a second diameter, wherein the second diameter is larger than the first diameter and the second wellbore tubing is downhole from the first wellbore tubing;
 orienting the casing removal tool within the second wellbore casing; 
 initiating the casing removal tool to remove casing from the second wellbore casing; and 
 retrieving the casing removal tool including the nozzle section from the wellbore, 
 wherein orienting the casing removal tool comprises anchoring the casing removal tool to an orientation tool that remains secured within the wellbore after the casing removal tool including the nozzle section has been retrieved from the wellbore. 
 
 
     
     
       27. The method of  claim 26 , wherein orienting the casing removal tool further comprises offsetting the casing removal tool from a radial center of the wellbore towards the casing. 
     
     
       28. A casing removal tool for a rigless removal of a portion of a wellbore casing from a wellbore, comprising:
 a tubular body configured to contain a thermite fuel mixture load comprising a gasifying compound and configured to initiate an exothermic reaction resulting in a molten thermite fuel, wherein the thermite fuel mixture load comprises an outer part adjacent to an inner diameter of the tubular body and a longitudinal axis at a central part of the thermite fuel mixture load, wherein the thermite fuel mixture load is configured to initiate along the longitudinal axis so that the thermite fuel mixture load reacts from the central part towards the outer part, whereby the outer part provides a thermal insulation against the exothermic reaction; 
 a nozzle array comprising a plurality of densely packed nozzles positioned on an external surface of the tubular body, wherein the nozzle array is configured to project the molten thermite fuel onto a section of the wellbore casing so that the molten thermite fuel from each of the nozzles in the plurality of nozzles at least partially overlaps the molten thermite fuel from each adjacent nozzle in the plurality of nozzles; and 
 an orientation lug configured to anchor into a downhole orientation tool.